Definition: You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
Input: Question: find the odd man out:1,3,10,21,64,129,356,777

 Option A: 3

 Option B: 10

 Option C: 21

 Option D: 64

 Option E: 356

Option D